Just for fun, I wondered how small a canonical hello world program could be in macOS running an ARM processor. Below is based on what I found here[0] with minor command-line switch alterations to account for a newer OS version.
ARM64 assembly program (hw.s):
//
// Assembler program to print "Hello World!"
// to stdout.
//
// X0-X2 - parameters to linux function services
// X16 - linux function number
//
.global _start // Provide program starting address to linker
.align 2
// Setup the parameters to print hello world
// and then call Linux to do it.
_start: mov X0, #1 // 1 = StdOut
adr X1, helloworld // string to print
mov X2, #13 // length of our string
mov X16, #4 // MacOS write system call
svc 0 // Call linux to output the string
// Setup the parameters to exit the program
// and then call Linux to do it.
mov X0, #0 // Use 0 return code
mov X16, #1 // Service command code 1 terminates this program
svc 0 // Call MacOS to terminate the program
helloworld: .ascii "Hello World!\n"
Assembling and linking commands: as -o hw.o hw.s &&
ld -macos_version_min 14.0.0 -o hw hw.o -lSystem -syslibroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX15.2.sdk -e _start -arch arm64
Resulting file sizes: -rwxr-xr-x 1 <uid> <gid> 16K Jun 18 21:23 hw
-rw-r--r-- 1 <uid> <gid> 440B Jun 18 21:23 hw.o
-rw-r--r-- 1 <uid> <gid> 862B Jun 18 21:21 hw.s
0 - https://smist08.wordpress.com/2021/01/08/apple-m1-assembly-l...